Defects reduction for a metal etcher

Abstract

A method of patterning a metal line and removing the polymer layer that forms on the metal lines sidewalls in an important post etch-polymer removal step (e.g., step 4). A semiconductor structure and an overlying dielectric layer, a first barrier layer, a metal layer; a second barrier layer and resist pattern are provided. A four step etch process is performed in sequence in the same etch chamber. In a first etch step (A), we etch through the second barrier layer using a B and Cl containing gas and a Cl containing gas in a reactive ion etch to form a first polymer layer over the sidewall of the second barrier layer. In a second etch step (B), the metal layer is etched exposing the first barrier layer to form a second polymer over the first polymer and the sidewall of the metal layer; the second etch step performed using a B and Cl containing gas and a Cl containing gas. In a third etch step (C), the first barrier layer is etched to form a third polymer layer over the first and second polymer layers. The third etch step is performed using a B and Cl containing gas and a Cl containing gas. In an important fourth etch step (D), we remove the first, second and third polymers; the fourth etch step performed using only chlorine containing gas (Cl ) gas and a fluorocarbon containing gas.